Method of separating impurities from lubricating oils



Patented Dec. l, 1942 WTHOD F SEPABATING URITIES FRG M LUBRIOATING OBIS Herbert H. Grcger, Washington, D. C. No Drawing. Application August 8, 1939,

Serial No. 289,075

Claims.

relates to the purification of the reconditioning This invention oil, and more particularly to of lubricating oil.

As is well known, lubricating oil over a period of time accumulates certain impurities, some of which are the products of chemical reaction and others of which are the result of mere mechanical; entrapment. It will also be appreciated that there are numerous filters adapted to mechanically remove the solid particles which are in suspension. Efiorts also have been made to remove from the oil certain impurities which are dissolved therein or which may .be of colloidal size, such as for instance carbon, gums, acids, metallic salts, etc. Ordinarily, such solutions and colloids cannot be removed by the usual mechanical filter, and various coagulants have been proposed to precipitate such impurities. Such precipitates are thereafter removed in various ways.

The coagulants heretofore used have been open to certain serious objections, particularly as applied to lubricating oil for an internal combustion engine. In general, it is desirable to have a. coagulant that is relatively insoluble in oil, relatively insoluble in water, that has a high boiling point, is relatively stable, and, particularly if it is to be used in conjunction with a cellulosic filter, the coagulant should have a low alkalinity in order to avoid destruction or digestion of the cellulose. The coagulants heretofore proposed have failed to meet one or more of these requirements.

An object of this invention is to overcome the disadvantages inherent in coagulants heretofore available in the purification of oils.

Another object of this invention is to provide a coagulant which possesses all of the above enumerated requirements.

Yet another object of this invention is to provide a relatively inexpensive coagulant which is highly eficient as a coagulant and which is also relatively stable.

To accomplish the above, and other important oblects as will be more fully apparent hereinafter, my invention in general embraces the concept of exposing a body of oil to a material which serves to coagulate all, or substantially all, of the carbon, metallic salts, and dust, and, to varying degrees, the gums and acids present in the oil. Preferably, the compound also is relatively insoluble in oil and water, does not readily vaporize, and does not attack the metal Parts or any filtering medium with which it is in contact. I have round that the guanidines 5 satisfactorily meet these requirements, and more particularly the substituted guanidine compounds such as those containing the phenyl, tolyl, or benzyl radicles, and cyanguanidine. It should be stated that the guanidine compound may include more than one of these radicles. In actual practice, I prefer diphenyl guanidine, principally because of its economy and availability, and I shall describe my invention with particular reference to diphenyl guanidine, although it is to be understood that other guanidines may be substituted in part or whole for the diphenyl compound. Other guanidine compounds which I have found especially eificacious are di-o-tolyl guanidine, triphenyl guanidine, and cyanguanidine.

While the exact amount of the guanidine used may vary with the exigencies of any particular operation, in actual practice I have secured excellent results by using in the neighborhood of one-quarter of one percent of the guanidinein other words, approximately ten grams of diphenyl guanidine to, one gallon of oil.

The precise application of the guanidine to the oil is likewise susceptible of wide variation. For instance, diphenyl guanidine, in powdered form, may be introduced in the oil, or of course a molded block of the material might be formed and introduced to a body of oil. Or again, a suitable solution of the guanidine as, for instance, in alcohol may be made up and such solution incorporated in the oil. Preferably, when a solution is desired, I make up a solution of equal parts of essentially anhydrous alcohol and toluene which will dissolve about ten percent of the guanidine. It should be pointed out that such a solution appears to be more reactive than when the guanidine in solid form is used.

As indicated above. my invention finds particular application in the reconditioning in situ of a lubricating oil for internal combustion engines, and in such case the guanidine compound may be located at any convenient position in the lubricating system. If filters are employed in the system, the guanidine may be suitably incorporated with such filters; and this is particularly desirable if the filter is of the fibrous type. In such case, the guanidine may be applied to the fibrous material in any suitable manner, such as by spraying, painting or by dipping the fibrous material in a guanidine solution, or by dusting the guanidine on the fibers if the former is in powdered form. Here again, the amount of guanidine used may vary appreciably, but in general I have used approximately combustion engine, it will of course be appreciated that my invention may be applied to the reclaiming of used lubricating oil. However, my invention finds particular application when used in a lubricating system in that the coagulant serves to remove the metallic salts as fast as they are formed. These salts act as oxidation catalysts, and consequently their removal retards the formation of the oxidation products such asgums and acids.

In general, I have found that oils treated in accordance with my invention are effectively purified, and that in the case of lubricating oil in an internal combustion engine, the period between oil changes is materially prolonged. In other words, if a filter is employed, the efiiciency of such filter is greatly increased. For instance, in actual tests, I find that when using diphenyl guanidine on a given oil, approximately twice as much time is required for such oil to build up a given percent of sludge over oil that is not treated with diphenyl guanidine.

While I have described my invention with particular reference to diphenyl guanidine, it will be appreciated that other compounds are included within the scope of my invention, and it is to be understood that my inventive concept is to be defined solely by the scope of the appended claims.

2. A method of separating impurities from lubricating oils comprising admixing therewith a relatively small proportion of diphenyl guanidine, and filtering the same.

3.A method of separating impurities from lubricating oils comprising admixing therewith a relatively small proportion of benzyl guanidine, and filtering the same;

4. A method of separating impurities from lubricating oils comprising admixing therewith a relatively small proportion of di-o-tolyl guani dine, and filtering the same.

5. A method of separating impurities from lubricating oils comprising admixing therewith diphenyl guanidine, said guanidine compound being in the proportions of approximately onequarter of one per cent by weight of the tota1- mixture, and filtering the same.

' 6. A method of separating impurities from lubricating oils which comprises admixing therewith a relatively small proportion of a compound of the guanidine series and filtering the same.

7. A method of separating impurities from lubricating oils which comprises admixing therewith a compound of the guanidine series, said guanidine compound being inthe proportions of approximately one-quarter of one per cent by weight of the total mixture, and filtering the same.

8. A method of separating impurities from lubricating oils comprising admixing therewith a compound of the guanidine series and filtering the same through an adsorbent filter.

9. A method of separating impurities from lubricating oils comprising admixing therewith I di-o-tolyl guanidine, said guanidine compound being in the proportions of approximately onequarter of one percent by weight or the total mixture, and filtering the same.

10. A method of separating impurities from lubricating oils comprising admixing therewith benzyl guanidine, said guanidine compound be-- ing in the proportions of approximately onequarter of one percent by mixture, and filtering the same.

HERBERT H. GREGER.

weight of the total 

